Method of treating a plurality of hydrocarbon oils for subsequent cracking



Aug. 25, 1942. v E. A. ocoN 2,294,126

METHOD OF TREATING A PLURALITY OF HYDROCARBON OILS FOR SUBSEQUENT CRACKING.

Filed Sept. 12, 1938 2 Sheets-Sheet 1 H/YT/-ra/mrma Hanny/37 A PE1/5F VH1. vf L -y C oNLBT/oN/NG *L Pl/M SL vos: Ris/005s -23 l r I INVENT OR.

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Aug. 25, 1942. E, A, OQON 2,294,126

METHOD oF TREATING A PLURALITY oF HYDRocARBoN w oILs FOR sUBsEQUENT GRACKING Filed Sept. 12, 1938 2 Sheets-$11891'. 2

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Patented ug. 25, 1942 UNITED' STATES PAT *Ni* orifice METHOD F TEATING AY PLURALITY 0F- HYDROCARBON OILS FORI SUBSEQUENT CRACKING 1 Claim.

This invention relates to anovelmethod and apparatus fory treating hydrocarbon materials, such as petroleum oils, preliminary to cracking treatments of the'heaver fractions of these materials. More particularly, this invention relates to a preliminaryl vaporization treatment in common ofv a plurality of carbonaceous materials having-diiferent characteristics with the aid of hot gases andvapors having a large part of the heat content they absorbed when produced in oil cracking processes.

By means 'ofY the present invention, the'v followingtypesof carbonaceous materials having different characteristics are fractionated inV a preconditioning and selective fractionatng tower, including its integral appurtenances, with a highly efficient heat exchange `between untreated and heat treated materials: (a) anfinitial uncracked charging stock, such as a crudeY petroleum oil including hydrocarbons ranging from gasoline constituents to those'more viscous than lubricatingfoil, (b) converted and'insurficiently converted hydrocarbons from a vapor phase cracking of distillate's', such' as'gas oil to produce gasoline, and (c) products from a'mild cracking or anon-carbonizing splitting treatment of reduced Ycrude oil to produceav high quality cracking stock distillate 'with a'minimum of gas and coke loss. Thi'spreliminary fractionating'treatment serves' advantageously to obtain from vaporized and unvapori'zed fractions at least two preconditioned streams of hydrocarbons having' different boiling ranges, each stream of hydrocarbons Abeingwell adapted for separate thermal conversion treatments to produce amaximum of high anti-knock motor fuels with a "minimum formation of gas and coke. An excellent heat balance is obtained in this' fractionation by an eflicient transfer of heatl from cracked or treated hydrocarbons to uncracked hydrocarbonsas both kindsI undergo 'distillation' and' fractionation, While" deleterious decompositionY products are segregated from straight run fractions of the uncracked hydrocarbons.` K

Systems commonly used in the past for cracking-'hydrocarbon oils entail inevitable heat losses and"'energy expenditure, since; in general, they involve van` independent tower for flashing or toppingf'acrud'eoil, an enlarged drum for soaking hot cracked materials by themselves, aseparatel fractionating tower forrefluxing separated vapor products of cracking, andnumerous pumps "and pipes for circulatinghot liquids Aand vapors be`v tween such units, all of which consume" andloseV a large amount of heat energy;

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A major object of the present'invention is to provide, in' general, a unification ofthe heated product separation with the preparation Aof charging stocks in order to eliminate heat dissipating vessels, such as partly detachedtovv'ers,

soakers, etc., and the multiple connections, found in the usual vast array of apparatus'used in cracking systems'. I Y

More specicobjects are contained inthepro- -visions for optimumV heat' transfer fronrheat treatment products with flexibility of control", for isolating reacted products from the charging stocks vof uncracke'd hydrocarbons, for dispensing with numerous individual h'eat'exchangeA units,

Y for proper' automatic regulation of temperatures in the combined fractionation operation, and for theV improved recovery of desirable end products.

Inpromoting the objects of 'this'inventio'ri use is m'adeof improvements disclosed and'cl'aimed in mypending applications Serial No; 67,l99,'filed March 5, 1936, and SerialNo. 189,136, filed February 7, 1938, which in turn carry 'forward novel ideas'described in my Patent No.`2,052,72l, filedV August, 1935, and granted September 1,1936. The'present application is a continuation-impart of application Serial No. 67,199, which discloses theuse of hot conversion products from "a cracked distillate containing virgin gas oil for' distilling acrude petroleum charging stock. Application Serial No. 189,136,sets forth asimilar preliminary distillation of crude oil together with mildly cracked reduced crude products. In the present invention hotp'r'oducts 'having substantially their conversion or heating coil exit temperatures'are introduced from a high temperature cracking coil and from" a'mild cracking `(coil into `a fractionation section' of Va column so that heat'liberated by their partialcondensation is efficiently reused'in distilling'the crude oilin an upper part of' the"colurnr1. v,

A further improvement providedV by this process comes from the novel multiple effect distillation of the crude oil which greatly reduces the amount of oil heating' in tube stills 'formerly practiced, since the eicient transfer of heat from' converted products undergoing partial condensation to crude undergoing distillation supplies substantially all of the heat necessary for`distilling the crude oil,"the additional v'heat or 'energy required being more efficiently provided by steam heat'or other heated volatile agents.'

Still additional improvements of the Vpres'fent process obtain in the use of means and'step's'for eliminating tars fromthe system,` in conditioning y 'the residual fuel oil 'products With spontaneous' use of their own heat, in cooperatively treating straight run, cracked, reformed and other heat treated motor fuel products together for purification and stabilization, and in recovering flexibly any type of petroleum products desired from the fractionating system, Whether it be highly aromatic motor fuel, a hydrocarbon-alcohol blend, a virgin quality gas oil cracking stock, a highly paraflinic Diesel fuel, or a high quality lubricating oil fraction. Thus it may be readily seen that the present invention makes an admirable advance with respect to the known combination cracking units, which have notoriously lacked adaptability and have been useful only in a large scale cracking of a single kind of crude oil when once constructed.

Further eludication of the aims, means, and method of this invention will be further made by reference to the drawings in which:

Figure 1, shows a sectional elevation View of a distillation and fractionation column with accessory apparatus in an elementary form for conducting the process;

Figure 2, shows in sectional elevation view a similar apparatus with modifications by which distillation and fractionation unit is composed of 2 columns in a series and which less of the cracked hydrocarbons become mixed with distillates of uncracked hydrocarbons.

In each of the figures corresponding parts are indicated by similar characters.

Referring to Figure 1, the main fractional condensation and distillation column or tower is designated by numeral I. The charging stock of crude or skimmed crude petroleum oil, or a similar composite hydrocarbon material of Wide boiling range, which may include coal tar oils or liquefaction products and hydrocarbons from other sources, is injected into tower I by pipe 2 at some low and intermediate point in the tower. The charging stock of crude may be injected into the tower at substantially an ordinary temperature or somewhat preheated, for example to about 400 to 600 F. Preheating of the crude oil may be accomplished by passing the crude oil through any heat exchange units or heating tubes found to be economically satisfactory, the heat exchange being with any hot products of the system or any other system. Cracked or heat treated products, such as a mildly cracked and fluidized heavy hydrocarbon distillate or residual fraction, at substantially a heating coil exit temperature of 650 to 850 F., and a well converted cracking stock or products of highly cracked gas oil at substantially a heating coil exit temperature of about 850 to ll F., are introduced at approximately the same point in the tower I or spaced there-below, as shown, by means of injection pipes 3, 4, and 6. Preferably, as illustrated, the lower temperature heat treatment products are introduced by either or both lines 3 and 4 below the pan 'I which is disposed to receive reduced crude from the charging stock. Line 5` introduces high temperature cracked vapors, while line S introduces separated liquid products from a high temperature cracking, preferably a coke and tar-free fuel oil, when such products are separated in the trap or separator 8.

Above the point of charge introduction from pipe line 2 are appropriately distributed and spaced plates, baffles, and pans for fractional condensation of such fractions as gas oil boiling in the range of about 450 to '700 F., Diesel fuel oil boiling in the range of about 400 to 600 F., kerosene boiling in the range of about 350 to 500 F., heavy naphtha. boiling in the range of about 300 to 475 F., so as to permit an overhead having an end point desired for gasoline to pass out of the tower through line 24. Each of such fractions respectively in the order named may be withdrawn separately at ascending points from tower I by lines 25, 26, 21, 28 and 24, as shown. Beneath each withdrawal plate or pan may be introduced refluxing fractions preferably of somewhat higher boiling end point by lines 29, 30, 3|, and 32.

By disposing a complete partition 33 so that gasoline and light naphtha vapors may be forced to pass through a sorptive contact mass or purifying agent in any of the vessels 34, which may be connected in parallel for alternate use and regeneration or refilling, and in series, the motor fuel vapors for explosion engines may be readily purified, or purified and stabilized then blended and homogeneously mixed with volatile antidetonation agents in an automatic and eiiicient manner never before achieved. Lines 33 and 35 are utilized for carrying blended cracked and straight run vapors to any of the vessels 34 and back, following purification, to tower I.

The vessels 34 may be provided with purifying adsorbents such as clays, fullers earth, silica gel, metal oxides, etc., or with liquid reagents flown countercurrently by introduction through inlets 36. Liquid reagents such as metal halides dislsolved in inert solvents, alkaline solutions, acids, salts, etc., may be employed. Also other well known substances capable of eliminating objectionable gum forming and objectionable sulfur containing compounds may be used in vessels 34.

The purified light naphtha vapors reintroduced into tower I by line 35 are then effectively blended with one or more volatile anti-detonating agents, such as alcohols, ethers, ketones, aromatics, aniline, other aromatic and aliphatic amines, or other branched chain organic compounds boiling in the gasoline boiling range, and any other desired type of volatile reagent boiling in the gasoline range, such as anti-oxidants, decarbonizers, solvents, etc., which are to be desirably homogeneously mixed with naphtha hydrocarbons in a final condensate of the resulting vapor blend, the nnal condensate being a finished motor fuel having boiling characteristics required by specifications. Such addition agents may advantageously be introduced by line 3l, so that they undergo distillation or fractionation in the remaining part of the upper tower or at least mutual condensation and mutual stabilization with the gasoline to form a finished product.

The upper part of the fractionation and distillation tower I, mainly above the complete partition 39, serves Vas a zone for homogeneously blending the described addition agents. Alcohol vapors which may comprise' methanol, or higher alcohols including their isomers, for example, a total alcohol product of fermentation, synthesized methanol products, etc., may be introduced above partition 39 to blend with the naphtha vapors. Simultaneously, other similar volatile blending agents may be introduced into this section of the tower so that the final overhead product is properly blended with addition agents boiling within its desired boiling range, e. g., antidetonating compounds, such as, organo-metallic compounds of lead, tin, or selenium, iron carbonyl, iospropyl ether, metal aminocarbonyles, etc., singly or mixed.

A tar trap or separator 8 may be interposed in theconnect'ing. linev 9 from av` heatingzone to remove, onlytarand. sludgeor both tar and heavy` liquids of` fuel oil quality. As shown,` separatorV 3 is of sufcient capacity to permit tar and sludge,

to settle to thebottom for withdrawal by drain pipe IQ., Separator B maybe provided with an inlet"l I .for injecting vaporizing agents and reactivegases such Vas, alcohol vapors, aromatics, xe'd hydrocarbon gases, water gas, producer gas, carbon monoxide, and steam to aid in tar separation, purification, and; to some extent in gas polymerization and catalyticcracking. Through the use of cracking catalysts avcompletionv of the cracking may bek obtained therein, alongmwith separation of non-volatile materials like tar and similarly high boiling fuel oil. Inlet 46 may be provided for introducing suspended chemical adbsorbents such as lime, clay, bauxite, floridin, diato'rnac'eo'us earth, fullerrs earth, broken brick, pumicepsand, unglazed clay rings, coal, coke, charcoal, ashes of coal, coke, charcoal, orV other similar solid carbonaceous material, clay treated withracids, such as phosphoricy acid, meta-phosphoric acid, pyro-phosphoric acid, ortho-phosphoric acid, singly or mixed. supernatant liquid fuel oil free from tar, coke, and sludge may be withdrawn from the separator by pipe 5 to be passedthereby to thev lower part of tower I, preferably maintained at a lower pressure than tar separator 8,

The lower part of tower I may be provided with baiflles I3 and I4 to aid sludge settling, so that a relatively clean fuel oil may be withdrawn by pipe I5 to a fuel oil conditioning drum I5 operated at a lower pressure than separator 8 and tower I. In such conditioning drum, conditioning and volatilizing gaseous agents, such as steam and ammonia, may be introduced by pipe II to. aid in removing light fuel oil vapors by line I8, leaving a conditioned unvaporized fuel oil of regulated fiash point and high purity to be withdrawn by pipe I9.

Below the charging stock injection point of line 2 may be provided any suitable number of plates, baiiies, and condensate pans, and withdrawal means, so that reduced crude may be collected and withdrawn from tower I, free from unvaporized productsl` of cracked hydrocarbons `introduced into the lower part of lthe tower as by pan 1 and line l2, while residuals and heavy distillates of cracked products may be collected and withdrawn from pan in the lower part of the tower as by line 2I. Reduced crude oil may be jointly collected with an unvaporized portion of a mildly heat treated reduced crude introduced by line 3 and to be withdrawn by line 2I when the heat treated product does not contain substantial amounts of materials which are readily carbonized upon a further heat treatment. Other injection means, such as pipe 22 for introducing reformed, polymerized or otherwise treated products, containing heavy residuals may be located in the tower where these products do not add tarry bodies to the reduced crude. A drain pipe 23 is provided at the bottom of the tower for removal of sludge, tars, and spent residues.

Figure 2, illustrates a unit in which the same general operations can be carried out as in the unit shown in Figure 1, but has differences of arrangement which allow the reduced crude and intermediate crude oil distillates to be obtained with little or no admixture of cracked products and which allow for a purification of naphtha vapors from cracked hydrocarbons separate from ing of such vapors.

As in the aforementioned operation described in Figure ,1, hot vapor` and liquid products pro-- duced by cracking ahydrocarbon distillate atelevated temperatures are introduced into` theV lower part of column I of FigureY 2, belowre-v taining means 20bylines 4, 5, 6, etc. This part of the column may be considered as the cracked hydrocarbon stripping and fractionation section and this section is separated from the crude distillation and fractionation section in the upper part of the column so that cracked vapors from the lower part do not mix with theV crude oil vapors in the upper part of the column. Vapors arising from cracked hydrocarbonsvin. the stripping `and fractionation section are flown upwardly in pipe 38 in which partial condensation of ,these vapors may occur as they indirectly transfer heat to crude oil hydrocarbons. Vapors withdrawn overhead from pipe 3S.by line 4I)- may be subjected to a further partial condensation in the heat exchange analyzer 4I wherein heat may be imparted to a charging stock upon con densing vapors boiling above a naphtha boiling,

range. Condensate from 4I maybe` joined via pipe 46 with gas oil withdrawn by pipe 25. vapors continuing from line 46, through analyzer 4I may then be subjected to purification in vessels 34 which are operated as previously described.

In the crude oil distillation and fractionation section in the upperpart of .column I, a crude oil is introduced throughpipe 2 above retaining means 2&3 for distillation and fractionation of the evolved vapors intointermediate distillatesV boiling above a napthaboiling range. Such in termediate distillates may be collected and withdrawn through the use of vseveral collecting and withdrawal means as earlier described. However, in addition a lubricating oil distillate may be removed by line 41. vapors from the crude oil are withdrawn and may be passed by line 24 to a blending zone in column ft2, which corresponds to the blending zone above partition 355, in Figure 1. A portion of such naptha vapors flowing through line 24 may be passed by line 43 to onev or more of the purification vessels 34, if desired. Purified vapors from vessels 34; may be joined with vapors from line 24 for common blending in-column. 42 wherein the volatile addition agents maybe employed, although at times it may be desirable to separately condense the purified and nonpuried vapors before further treatments. A nal condensate is collected in receiver 44 from vapors passed to a cooler 45 which is controlled to obtain a liquid fuel having a specification boiling range. Receiver 44 may have the usual fixed gas and liquid outlets.

In accordance with the procedures described it is to be noted that a composite of uncracked. hydrocarbons having a wide boiling range, as exemplified in a crude petroleum oil, is sub-- jected to distillation and fractionation in heat exchange with heat treated hydrocarbons simul taneously undergoing fractionation, and that this heat exchange is effected in a manner which permits a good recovery of heat used in cracking processes while deleterious products of cracking such as tars and other readily carbonizable materials are prevented from contaminating fractions recovered from the crude oil. These results are preferably obtained by bringing the cracked or otherwise heat treated hydrocarbons into a straight run naphtha vapors prior to a. blend Fractionated naptha definite heat exchange relation and coordination as featured by the following steps:

Preferably hot vapor products produced by cracking a hydrocarbon distillate, such as a gas oil, are separated from any tarry products while 'maintained at substantially their cracking temperatures of about 850 to 1050 F. Almost immediately thereafter, while being approximately at the same temperature, they are intimately contacted with hot products of a mildly cracked reduced crude, thus these vapors prior to any substantial condensation after leaving a cracking zone exert a stripping action upon the volatile constituents of the mildly cracked reduced crude being admitted into their presence at a mild cracking temperature of about 650 to 850 F. The remaining hot vapor products of the cracked distillate joined with the volatiles stripped from the mildly cracked reduced ciude are then led into heat exchange or contact with a crude oil to which they impart sufficient heat for distillation even though the crude oil be not preheated to any substantial extent, or, if preheated, being so without substantial decomposition.

Surprising good results are obtained from the coordination of steps involved in this process. Fuel oil recovered directly from the process is .lof high quality in being substantially free from fasphaltic tarry and coke bodies, and requires no `expensive filtering treatment. A maximum re- ;covery of heat is obtained from the heat input for a cracking operation with reduction of apparatus and handling of materials. A crude oil is subjected to distillation by the heat recovered from cracking without substantial decomposition or contamination by deleterious asphaltic or tarry products of cracking.

The exact sizes of apparatus and conditions depend upon the capacity of the plant, the character of the charging stock, and types and specications of the final products desired. Instruments, valves, pumps, temperature and pressure indicators, recorders and controllers, iiow control valves, meters, gauges and other such engineering equipment are not all shown or mentioned, but it is understood that they will be used as required and as understood in the art.

The pressures used in column I, will depend upon the character of the charging stock, and iinal products desired, and may be operated at substantially atmospheric, several pounds above atmospheric or superatmospheric, for example, in the range of from about to 600 lbs. per square inch.

Although the heretofore described method is preferred, the 4system of operation may vary considerably as there are characteristics in structure and apparatus which make my invention one of broad application; and I do not desire to limit the apparatus to use in connection with the process, nor to the details of construction. It will be understood that the above examples and illustrations are not to be considered as limitations on the principles of the invention set forth and while I have described by invention and methods and apparatus of carrying it into practice, it is to be understood that modifications and changes may be made provided they do not depart from the scope of the invention and the claim covering the invention.

I claim:

A process for distilling and fractionating a crude petroleum oil in heat exchange with heat treated hydrocarbon products undergoing fractionation, which comprises contacting the hot products produced by cracking a hydrocarbon distillate to lower boiling hydrocarbons with a catalytic adsorbent to complete the cracking reaction and to precipitate tars and fuel oil higher boiling than gas oil, passing the remaining hot products in the vapor phase without substantial condensation into contact with the hot products obtained by a non-carbonizing splitting treatment of a reduced crude to strip volatiles therefrom, passing such volatiles combined with such remaining hot vapor products of the cracked distillates prior to condensation into a distillation zone wherein they are mixed with and transfer heat to a petroleum crude oil undergoing a noncracking distillation, separating tars and sludge from said fuel oil precipitated from the hot products of the cracked distillate combining said fuel oil thus freed from tar and sludge with an unvaporized portion of said hot products obtained by a noncarbonizing splitting treatment of reduced crude, and conditioning the combined fuel oil and said unvaporized portion of the reduced crude given said non-carbonizing splitting treatment to form a fuel oil of desired ash point.

ERNEST A. OCON. 

